Abstract: Haematological profile of an animal is the reflection of its immunological status. Fishes are prone to infections by several pathogens which influence the immunity of the affected individuals. The effect of three probiotics on four haematological parameters viz., level of haemoglobin, total erythrocyte count, total leucocytes count hematocrit/packed cell volume of Indian magur (Clarius batrachus L.) was studied over a period of eight weeks. The level counts of all these four parameters decreased significantly in the blood of fish administered with pathogenic organisms as compared to the control; the fish administered with pathogenic organisms died after three weeks. The level counts of hematological parameters showed significant increase in the blood of fish treated with probiotics alone versus control and also in fish administered with pathogenic organisms versus probiotics. A comparison among the three probiotics revealed that, probiotic 1 was more effective than probiotic 3 and probiotic 2; the effect of latter stood at the lowest level.